International Journal of Plant Science and Ecology Vol. 4, No. 3, 2018, pp. 22-33 http://www.aiscience.org/journal/ijpse ISSN: 2381-6996 (Print); ISSN: 2381-7003 (Online)

Evaluating the Classical Statistical Methods and Gradient Analysis of Soil-Vegetative Cover Interrelationships (Case Study: Steppe Pastures in Arsanjan County-)

Saeed Mohtashamnia 1, *, Mohammad Javad Eskandari 2

1Department of Agriculture and Natural Resources, Islamic Azad University, Arsanjan Branch, Arsanjan, 2Department of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran

Abstract The vegetative cover well-establishment subject to matrix governance is inter alia the most important environmental factors. Gaining an insight over the entire factors and comprehending their interrelationships with the quantitative attributes of the vegetative cover can be done through classical statistical methods. But, the existence of some relationships in the hidden structure of the environmental factors render classical statistical methods inefficient and unable to accurately demonstrate these collateral relationships. Therefore, the use of gradient analysis can precisely reveal the hidden structure and then the authentic ecological grouping of the plant species can follows. Based thereon, the most important factors associated with the soil were identified to determine the ecological plant groups inside and outside a protected area both of which featuring similar topographical and climatic conditions. In each area, the measurements of canopy percentage as well as the density and frequency of the plant species based on random-systematic sampling method via placement of 5 transects, 50 meters in length, and placement of 10 quadrats, 1 square meter in area, based on antenna method were carried out so as to better exploit the appearances of the pasture surface. Moreover, the soil samples were taken according to the boundary-layer separation horizons and the type of the extant plants considering the active rooting region from two depth ranges of 0-10 cm and 10-50 cm in a completely systematic manner of the beginning, middle and ending sections of every transect. The regression analysis results indicated that, out of the 6 ecological plant groups from both of the studied areas, there is a relationship between Amygdalus lycioides, Acantholium festuacemum, Artemisia sieberi and stipa barbata and the twelvefold soil variable based on classical statistical methods but no particular behavior was evidenced in the classical statistical methods regarding the two species of Convolvulus acanthocaladus and Ebenus stellata. But, the utilization of PCA and CCA methods and drawing of raster graphs and making of classifications finally led to the identification of the soil factors influencing the establishment of these two species in both inside and outside the conserved area.

Keywords Gradient Analysis, Protected or Conserved Area, Soil Characteristics, PCA, CCA

Received: August 17, 2018 / Accepted: September 10, 2018 / Published online: October 9, 2018 @ 2018 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY license. http://creativecommons.org/licenses/by/4.0/

well perceived in the natural ecosystems so as to be able to 1. Introduction appropriately manage the pasture and rangeland ecosystems. According to the importance of the vegetative cover as the The relationships between the ecological factors should be key factor of the pasture ecosystems and considering the

* Corresponding author E-mail address: 23 Saeed Mohtashamnia and Mohammad Javad Eskandari: Evaluating the Classical Statistical Methods and Gradient Analysis of Soil-Vegetative Cover Interrelationships (Case Study: Steppe Pastures in Arsanjan County-Fars Province) involvement of the environmental factors in the temperate and dry, semiarid and temperate, semiarid and cold determination and change of their composition and structure, and subhumid and cold climatic conditions, and Amygdalus it is necessary to recognize the most important environmental orientalis species are present in two subhumid and cold factors influencing the establishment and the scattering of climates and on higher elevations [4]. [17]. dealt with the plant communities. In fact, these factors provide for the investigation of the close relationships between several plant establishment of various plant species in the rangelands and species characteristic of dry regions with some of the various pastures. Also, knowing that there is a close relationship environmental and soil-related factors and determined the between the ecosystem components and that the soil is fully most important factors influencing their scattering in a part of subjected to the climatic factors, living organisms, Shahriyar’s Chaharbaq pastures. His study results indicated topography, mother rock and time, the discussions become that the most important factors influencing the region’s more connected to the soil-vegetative cover interrelationships scattering of vegetative cover are soil texture, salinity and [16]. Keeping it in mind that the investigation of the minerals’ percentage, effective soil depth, potassium and ecological plant groups belonging to conserved areas and nitrogen levels [7]. [20]. applied the geographical otherwise is largely feasible via taking the environmental information system to investigate the relationship between factors, especially the soil, into account, the classical the plant communities and the physical factors in Chorat sub- statistical methods can be utilized to perform regression basin from Telar watershed in the northern section of Alborz analyses and unravel the relationships’ being statistically mountain range. The study results indicated that the climatic significant or not in 95% and 99% confidence level so as to factors influence the plant types and biological forms and, in figure out the effectiveness of the soil-related variables on the the meanwhile, the rangeland plant types are sensitive to the vegetative cover establishment. But, the presence of some soil factors so the soil-related variables are to be considered variables featuring hidden structures degrades the accuracy as the most important factors behind the region’s vegetative of the classical statistical methods that are mostly incapable cover scattering [17]. [9]. evaluated the relationship between of revealing these hidden structures so the task can be the soil’s chemical and physical characteristics with some of assigned to gradient analysis methods in such cases [16]. Sabzevar region’s index plants. The study results indicated Thus, the present study adopts an approach to determine the that there is a significant relationship between the soil index plant species residing in rangelands inside and outside characteristics and the vegetative cover percentage of the the specified protected area to, finally, separate the ecological various plant species but the correlations between them vary plant species based on vegetative cover variables and soil as depending on the plant species [10]. Studied the most well as investigation of the most important soil-related important environmental factors influencing the scattering of factors influencing the vegetative cover using the statistical wormwood in steppe pastures of Fars Province. The results classical and non-classical methods. There are numerous of their study showed that the highest environmental factors’ studies carried out both inside and outside the country in line occurrence likelihood in respect to Artemisia sieberi, in an with the present study subject matter. [5]. studied the mutual elevation gradient of 1900-2200 meter goes to phosphorus, relationships of the soil’s physical and chemical acidity, presence of sand, elevation from sea level, as the characteristics with the dominant rangeland plant species in preliminary factors, followed by the percentages of lime, Mehr-e-Zamin region, Qom Province. Their results indicated gypsum and potassium, as the secondary factors; that the various soil parameters do not exert identical effects furthermore, the highest environmental factors’ occurrence on the plant species and the canopy, amongst the various likelihood in respect to Artemisia aucheri, in an elevation studied soil-related factors, is maximally correlated with two gradient of 2200-2400 meter, belongs to sand, elevation from factors, namely potassium level and horizon thickness rates, sea level, as the primary factors followed by the percentages and minimally associated with electrical conductivity [1, 7]. of potassium and clay and the slope as the secondary factors dealt with the study of the relationship between the climatic [11]. [8]. studied the relationship between the vegetative factors, topographic and edaphic factors with the vegetative cover and environmental factors in dry rangelands on cover in the mountainous rangelands in Rinne. Their results calcareous soils of the eastern Slovakia. In the study, three indicated that the environmental factors of the region have a substantial factors, topography, soil and biological factors great effect on the vegetative cover and the soil’s physical were examined. The study results indicated that these three and chemical characteristics inter alia the various factors factors because separation in the plant types of the studied exert the highest influence on the region’s plant communiteis region in such a manner that inter alia all the studied factors [3]. Investigated the ecological factors influencing the the sun irradiation intensity, soil depth and slope play scattering of the various almond species in Ilam Province. determinative roles [16]. Applied principal component The study results indicated that Amygdalus lycioides and analysis (PCA) and regression analysis to investigate the wild almond amygdalus scoparia species reside in four relationships between the plant communities and International Journal of Plant Science and Ecology Vol. 4, No. 3, 2018, pp. 22-33 24

environmental factors of wetlands and their peripheral meter quadrats for both of the protected area and the region regions in the upper and lower sections of Tarim River in a at its side. The quantitative vegetative cover variables study. Their study results indicated that the plant community measured herein included the percentage of land cover as distribution is directly correlated with moisture, minerals and well as the frequency and density of the plants along organic constituents of the soil [20, 19]. investigated the transects and inside the quadrats. To carry out edaphological correlations between the desert plant communities and the studies in every quadrat according to the boundary-layer soil-related factors in the southern margin of Tongot’s separation horizons and the type of the extant plants and Gorban desert by taking advantage of hierarchical considering the active rooting region, samples were taken classification method and principal component analysis. The from two depths of 0-10 Cm and 10-50 Cm and then the results of the PCA indicated that there is a special samples were subjected to physical and chemical relationship between the soil-related factors and plant examinations. The analysis of the vegetative cover data and communities in such a way that pH, organic matter and soil the soil data was conducted in PC-Ord software as follows: salinity were found out as the most important factors firstly, the data pertaining to density and frequency were bringing about changes in the soils of the various plant subjected to preliminary preparation and then inserted to communities [19]. Yumin Yo et al (2008) evaluated the Excel and PC-Ord environments in separate for each region. vegetative cover in connection with the ecological and DE trended correspondence analysis (DCA) method was geological factors in karstic regions in the southwestern parts applied to delineate raster graphs and Two-Way Indicator of China through making use of conventional comparative Species Analysis (TWINSPAN) was employed to classify the analysis. Their results indicated that soil moisture and vegetative cover. According to the weak eigenvalues calcium carbonate play the greatest parts in the region’s obtained for the canopy, there was made use of frequency scattering of vegetative cover. They also expressed that the and density data based on DCA method as well as the conventional comparative analysis is a powerful instrument frequency data in the classification method. The data were for demonstrating the vegetative cover changes [18]. inserted in the software environments and then underwent analysis. Also, there was made use of correlation and 2. Method regression analyses in order to determine the relationships between the soil variables and vegetative cover. The study region is located in the vicinity of Arsanjan County in a 120-km distance in the northeast of and 3. Result on the kilometer five of the Arsanjan-Sa’adatshahr road. The region is stretched on 53° 12´ 38˝and 29° 52´ 22˝ to 53° 23´ Protected Area: 10˝and 29° 58´ 41˝geographical coordinates. Figure 1 The results obtained from the investigation of the protected illustrates the study region. area’s percentage of vegetative cover indicated that Based on Ambergeh method, the region was found having a Convolvulus acanthocaladus and Amygdalus lycioides, semiarid and temperate climate featuring an average rainfall respectively, account for 3.68% and 3.55% of the vegetative of 250 mm. The protected area is part of Arsanjan’s Forestry cover. The foresaid species along with Artemisia sieberi and Plan for conservation of Bonab Jungle. The foresaid region Ebenus stellata were the dominant plant types of the region. has been protected since 1975. Arsanjan’s Forestry Plan has The results of the frequency measurements indicated that been implemented in line with conservation and reclamation Ebenus stellata and Lactoca orientalis account for 38% of the of part of the almond and Persian turpentine tree jungles in perennial plant species residing the region. The results of the Fars Province based on the instructions issued by the investigations on the vegetative cover percentage outside the Organization of the Country’s Jungles and Pastures. The protected area showed that Convolvulus acanthocaladus and region outside the protected area is situated on the left hand Ebenus stellata account for 6.24% and 3.06% of the prevalent side of the trail road connecting Arsanjan to Sarpaniran and vegetative cover of the region, respectively. Amongst the adjacent to the protected area both of which feature similar other plants coexisting the region Artemisia sieberi and climatic and topographical characteristics. The region is in amygdalus lyciodes can be pointed out. Table 1 presents the the midsection between the summer and winter pastures used measurement results pertaining to vegetative cover of the by the nomads and traveling clans of Fars Province and a lot plants both inside and outside the protected area. The results of domestic animals graze on the wooded and unwooded of the frequency measurement indicated that Convolvulus pastures [8]. To perform the study, there was made use of a acanthocladus and wormwood (Artemisia sieberi) account for randomized-systematic sampling method with five transects, 24% and 22% of the vegetative cover, respectively. 50 meter in area, along which there were selected ten one-

25 Saeed Mohtashamnia and Mohammad Javad Eskandari: Evaluating the Classical Statistical Methods and Gradient Analysis of Soil-Vegetative Cover Interrelationships (Case Study: Steppe Pastures in Arsanjan County-Fars Province)

Table 1. Measuring the percentages of land cover variables in the protected area and unprotected area.

Measured variable Protected area Unprotected area Canopy 48.75 21.06 Humus 13.89 4.36 Pebble and detritus 1 1.56 Bare soil 37.25 73.02 Also, the diagram (1) depicts the comparison of the measured variables in both inside and outside the protected area.

Figure 1. The study region’s position.

Figure 2. Measuring the land cover variables in the protected and unprotected areas.

Figure 3. Comparing the soil texture components of the protected and unprotected areas. International Journal of Plant Science and Ecology Vol. 4, No. 3, 2018, pp. 22-33 26

Figure 4. Comparing the lime factors in protected and unprotected areas.

Figure 5. Comparing the gypsum factors in the protected and unprotected areas.

Figure 6. Comparing the basic saturation factor in protected area and unprotected area. 27 Saeed Mohtashamnia and Mohammad Javad Eskandari: Evaluating the Classical Statistical Methods and Gradient Analysis of Soil-Vegetative Cover Interrelationships (Case Study: Steppe Pastures in Arsanjan County-Fars Province)

Figure 7. Comparing the organic carbon factor in the protected and unprotected areas.

Figure 8. Comparing the electrical conductivity in the protected and unprotected areas.

Figure 9. Comparing potassium factor in the protected and unprotected area. International Journal of Plant Science and Ecology Vol. 4, No. 3, 2018, pp. 22-33 28

Figure 10. Preliminary rastering of the plant species based on PCA method.

Figure 11. The results of Monte Carlo test based on CCA method. 29 Saeed Mohtashamnia and Mohammad Javad Eskandari: Evaluating the Classical Statistical Methods and Gradient Analysis of Soil-Vegetative Cover Interrelationships (Case Study: Steppe Pastures in Arsanjan County-Fars Province)

A) The Measurement Results of Soil’s Physical and Chemical Properties: The measurement results of the soil’s physical and chemical characteristics are given in table 2 and displayed in diagrams (3), (4), (5) and (6).

Table 2. Comparing the measurements of the physical and chemical characteristics of soil in protected and unprotected areas.

Soil characteristics Protected area Unprotected area Sand percentage 46.5 40.7 Silt percentage 42.2 47.1 Clay percentage 11.3 12.3 Lime percentage 45.1 35 Gypsum percentage 1.023 0.834 Basic saturation percentage 38.4 32.2 Organic carbon percentage 0.434 0.72 Electrical conductivity 0.39 0.448 Nitrogen percentage 0.043 0.071 Phosphorus percentage 15 17.73 Potassium percentage 409.2 341.2 B) The Results of Correlation Test between Canopy Percentage and Soil Variables: The correlation test results of the relationship between the soil variables and canopy are summarized in separate in table 3.

Table 3. Correlation coefficients of the soil variables with the canopy percentage of the indicator species of the protected and unprotected areas.

Indicator genus Amygdalus Ebenus Acantholimon Artemisia Stipa Convolvolus

Caso 4% Protected area 0.337 -0.243 0.717 *** 0.165 -0.249 -0.373 Unprotected area 0.664 ** -0.144 0.504 -0.451 -0.779 -0.166

Caco 3% Protected area 0.007 0.057 0.314 -0.298 0.781*** -0.036 Unprotected area 0.434 0.081 0.667** -0.063 0.129 -0.241 Clay% Protected area 0.352 0.043 -0.374 0.328 0.432 * 0.020 Unprotected area -0.371 0.140 -0.413 0.151 0.394 -0.250 Silt% Protected area 0.204 0.257 0.178 0.433 * 0.247 -0.127 Unprotected area -0.521 0.473 0.042 0.473 0.429 0.007 Sand% Protected area -0.575 * -0.259 0.005 -0.551 ** -0.426 * 0.109 Unprotected area 0.626 * -0.506 0.090 -0.510 -0.544 0.073 N% Protected area -0.348 -0168 -0.312 -0.191 -0.145 0.099 Unprotected area 0.028 -0.256 -0.348 -0.156 -0.186 0.015 P% Protected area -0.242 -0.209 -0.265 0.241 -0.251 0.074 Unprotected area -0.489 -0.259 -0.508 0.641 ** -0.204 0.057 K% Protected area -0.085 -0.171 -0.501 ** 0.557 ** 0.294 -0.003 Unprotected area -0.621 -0.216 -0.597 * 0.802 *** -0.016 -0.122 OC% Protected area -0.125 -0.161 -0.304 -0.180 0.152 0.096 Unprotected area 0.021 -0.253 -0.352 -0.152 -0.184 0.018 SP% Protected area 0.054 0.196 -0.193 0.443 * 0.498 ** -0.125 Unprotected area -0.720 ** 0.403 -0.405 0.478 0.569 * -0.159 EC Protected area -0.190 -0.330 -0.268 .0.341 -0.277 0.088 Unprotected area -0.324 -0.470 -0.433 0.677 ** -0.396 0.026 pH Protected area 0.229 -0.047 0.332 0.160 0.106 -0.381 * Unprotected area -0.207 0.262 -0.184 -0.013 0.536 -0.340 International Journal of Plant Science and Ecology Vol. 4, No. 3, 2018, pp. 22-33 30

C) The Regression Analysis Results and Regression Model Offering: The regression results and regression model offering findings of the indicator species both inside and outside the protected area along with the twelvefold soil variable are tabulated in table 4.

Table 4. Regression equations.

Indicator species name Regression equation R2 0.63Caco +0.22Caso +0.194clay+0.103Silt -0.21Sand-0.152 N-0.157 OC+0.069 K-0.119 P+0.01 SP-0.077 Amygdalus lycioides 3 4 63% EC-0.097pH+1.788 0.275Caco +1.849Caso +3.729Clay+14.887Silt+20.043Sand-5.957 N+5.687 OC+0.524K+0.57P+2.928 SP- Ebenus stellata 3 4 81.3% 2.573EC-8.46pH 0.516Caco +0.387Caso -0.281Clay-0.15Silt+0.279Sand-0.019%N+%OC-0.213%K-0.053%P- Acantholimon festucacemum 3 4 51.6% 0.232%SP+0.033EC-0.025pH+ 1.103 -2.304Sand+1.123 K+0.927Caco +0.129Caso +0.174Clay-0.379Silt-0.152N-0.132OC- Artemisia sieberi 3 4 0.15P+0.221SP+0.155EC-0.053pH+1.181 -2.694Caso -0.026Caco -0.038Clay-0.041Silt+0.086Sand-0.6N-0.083 OC-0.177 K-0.176 P-0.033 Stipa barbata 4 3 78.4% SP+0.2EC-0.242pH+4.42 91.891-0.689Caco -5.894Caso -5.204Clay-13.406Silt-15.955Sand+4.974 N-4.367 OC-2.943 K+1.55 Convolvolus acanthocladus 3 4 P+1.009 SP+2.248EC-21.024pH Also, the results of the direct gradient analysis aimed at the determination of the dominant ecological plant group in relation to the most important environmental factors were obtained by making use of PCA method in PC-Ord software environment. These results have been presented in Figure 10.

Figure 12. Comparing the phosphorus factor in protected and unprotected areas.

To perform the final grouping and verify the raster graphs to annual species. In this grouping, Acantholimon and based on PCA method using TWINSPAN classification Amygdalus were obtained as right differential that is method, the final ecological grouping was again evaluated. consistent with what was found based on PCA method. To The results indicated that Acantholimon festuacemum and determine the most important environmental factors Ebenus Stellata, as a primary group, are two most dominant influencing the formation and establishment of the major species living in the region; furthermore, Artemisia sieberi ecological groups of the region, CCA method and Monte and Convolvolus acanthocladus were found in TWINSPAN Carlo test were employed. The results of these tests have outputs as not being left or right differentials but as species been demonstrated in figure 11. completely scattered as regional-level groups even in respect

31 Saeed Mohtashamnia and Mohammad Javad Eskandari: Evaluating the Classical Statistical Methods and Gradient Analysis of Soil-Vegetative Cover Interrelationships (Case Study: Steppe Pastures in Arsanjan County-Fars Province)

Figure 13. Comparing nitrogen factor in protected and unprotected areas.

area be negatively associated with plant species which was 4. Discussion found positive in the unprotected area. Due to the high presence of potassium in Iran’s soil and its important role in The study results indicated that there are 26 families, 79 plant nutrition, more scattering and diversity come about genus and 109 species living as the flora constituents of the where this element is found in abundance. And, this same region. In spite of a multiple-year drought, the mean canopy effect of potassium was well evidenced in the scattering of percentage of the protected area was 48.75 which were the wormwood species. [7] Introduces soil’s content of 21.06% for the region adjacent to the protected area. potassium as one of the characteristics contributing to the Generally, the results of the vegetative cover quantitative larger fertility and scattering of the habitats of Artemisia characteristics measurements showed that Convolvolus species. Also, [20] mentions the amount of potassium acanthocladus and amygdalus lycioides in the protected area existent in the soil as the characteristic of the soil in the and Convolvolus acanthocladus and Ebenus stellata in the habitats of Artemisia. And, [7] in his study enumerates the region at the side of the protected area are the major amount of potassium as one of the important characteristics dominant species types. According to the history of the of the soil where shrubs are more prevalent., as well, states region that is amongst the last spots of Turanian Iran’s dried that the high potassium to magnesium ratio is appropriate for forests, changes were found in the vegetative cover dynamics the growth of shrubs while the low potassium to magnesium in the course of time in such a manner that amygdalus ratio is more auspicious for the growth of grasses. According lycioides species have been previously present in the to the high correlation found between potassium and substrate of the Persian turpentine trees. But the ecological Artemisia Sieberi prevalence, the present study results also outcome stemming from the absence of these trees due to showed that there is a positive relationship between the overexploitation led to the establishment of Ebenus Stellata species scattering and the increase in potassium levels. There in a vast area of the region. The results of the measured soil was not found any significant relationship between Ebenus variables were reflective of the significant relationship Stellata and any of the soil parameters measured based on between Amygdalus lycioides species presence and the classical methods of correlation test and this might have been percentage of gypsum resulting from the region’s geological due to the hidden structure of the soil variables considering formations; in addition, there was not found any significant the classical statistical methods. The hidden structures were relationship between the species presence and the other soil- completely revealed in the gradient analyses in such a way related variables. In the meantime, due to the occurrence of that there was found a significant relationship between the erosion in the region just outside the protected area, the phosphorus and gypsum percentages with special species resultant sand was found exerting a considerable effect in the growth in the protected area. establishment of the species in such a way that due to the existence of canopy and annual species in the protected area, especially during spring the humus resulting thereof acts as a 5. Conclusion protective layer and the active rooting of the plants causes the As for Convolvolus Acanthocladus, factors other than the soil particle to disintegrate and finer rather than coarser twelvefold soil variables were found having an effect and this particles will be formed accordingly. The same issue has was documented in the gradient analysis the results of which made the sand percentage of the soil profile in the protected International Journal of Plant Science and Ecology Vol. 4, No. 3, 2018, pp. 22-33 32

indicated that the species is meaningfully correlated with the method, it was found out that there is a correlation between percentage of silt existent in the soil texture. Regarding Convolvolus acanthocladus with the soil’s percentage of silt Acantholimon festuacemum, the results indicated that there is and this same finding was not confirmed in the correlation a positive and intensively significant correlation between tests. Also, critical component analysis (CCA) indicated that

Caso 4 and the species in the protected area. In other words, the ecological group Ebenus Stellata is correlated with the the species scattering increases per every unit increase in percentages of phosphorus and gypsum while the indirect gypsum level, whereas the same relationship was not found gradient analysis was not suggestive of any significant outside the protected area. The species was found positively correlation between the foresaid species and any of the correlated with Caco 3. The regression equation offered measured soil parameters. Moreover, the regression model herein, as well, produced significant results for the soil’s designed herein for the general evaluation of Ebenus Stellata variable of Caco 3. The results of the correlation analysis species establishment did not offer significant results. In indicated that there is a positive relationship between the soil addition, the results illustrated in figure 11 show that in the moisture both inside and adjacent to the protected area with four coordinate spots, the most important soil variables Stipa Brabata while a negative and highly significant influencing the prevalence rates of ecological groups relationship was evidenced between the species and lime in Acantholimon and Amygdalus are acidity and potassium the protected area; but, the relationship did not hold outside percentage which is reduced to silt percentage for the the protected area. Generally, based on the results obtained ecological group Artemisia and Convolvolus and, finally, the from raster graphs and classification operation, it was found percentages of phosphorus and gypsum for the ecological out that the dominance of the ecological groups group Ebenus Stellata. 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